The present invention relates to an obstacle detecting system, and in particular to an obstacle detecting system which is mounted on a vehicle for detecting an obstacle at a frontward direction thereof by using a radar principle.
Conventional obstacle detecting systems of the type are disclosed in Japanese Patent Laid-open Print No. Hei 1-114550 published in May 8, 1989, and Japanese Patent Laid-open Print No. Hei 2-216080 published in Aug. 28, 1990. In each of the conventional systems, a radio wave of an ultrahigh frequency is emitted from a following vehicle to a preceeding vehicle as an obstacle. If the wave is found to be the reflection from the preceeding vehicle, the resulting recognition is used for controlling the inter-vehicle distance.
However, in each of the conventional systems, since the beam of the radio wave is narrow in width or the lateral length direction of the vehicle, if the preceeding vehicle is moved in a direction which is substantially perpendicular to the cruising direction of the following vehicle, the chasing of the preceeding vehicle may be in malfunction.